Cyberpunky

Sorry for slow response. I checked mine this morning. Normally I just restart until it runs properly, but today I waited till wideband had woken up and it was lean. After a restart it was fine AFR's normal, and purring. I did a few trips today and at one point it was just a little off, I didn't think to check AFR's but noticed at lower revs it bucked , but once revs were a little higher, it was fine

Droops83

Again, you guys need to datalog the poor running conditions and compare them to when it is running well. Post screenshots here, or send log files. We can help!

shortyboy

Got some logs. Its labeled good start and bad start. You can see the bad start is lean across the whole tune. I got a good start, ran the car until warm up. then shut down and restarted, then got the bad start condition logs.

gpr8er

Just to bump the thread, my car is running great. Low speed driveability is damn near perfect. I still need to get the boost control situation figured out. Drove around for a couple of hours today with the MBC I have currently installed and hit overboost protection, it's like throwing out the anchor.

shortyboy

What type of injectors is everyone using? I know that vems can use low and high Z injectors but I'm currently using low Z and was wondering if it could be the culprit of my issue?
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Cyberpunky

I am using Gen IV High Z 80# injectors that came with Rogue M tune, So I don't think its the injectors.

mdnt08

I'm running high impedance dekas, but was running the oem low z with the PWM card channels. I have volvo injectors if you want to try do start and idle tests with them. I had them running when I was in NA mode.

shortyboy

Hmm. Back to the drawing board. Do you know if you have FAE or OEM Bosch speed reference sensors? And if you have the updated bracket with sleeve?

Thanks but I found out that one of my injectors were bad and swapped in a spare set. I also didn't know the set I had in was 72#s, I thought they were 55#s. And the set I put in I thought were 52# are actually less, 52#s at 3.8bar. I'll just retune it for now while I save for a set of deka high Z 80#s. Regarding the pwm channels, do you need to change it when switching from high Z to low?

Raceboy

You need to either enable or disable PWM in Base Setup -> Injector Settings (For high-Z: Injectors PWM DC 100%, Injector PWM Peak Time 25.5 ms, for Low-Z: Injectors PWM DC 35%, Injector PWM Peak Time 1.0 ms).
And also adjust req_fuel due to the flow rate difference in Base Setup -> Engine Setup.

shortyboy

Thanks Peep, Ive adjusted req_fuel for the time being and did some auto tuning. Would these fit?https://fuelinjectorconnection.com/c...ies-80-lb-deka I noticed they have another same model different height at 60mm. Thanks, BTW, waiting for email instructions for EBC solenoid install and settings. Im also going to replace and re-gap speed reference sensors with OEM bosch.

Raceboy

60mm overall height won't wit.

Droops83

Hi Wayne,

I just checked out your log files, and there definitely seems to be some sort of trigger/interference issue with the engine speed sensor(s).

I attached screen shots below---in the "good start" file, you can clearly see that the engine is "idling" at about 2000 RPM, while in the "bad start" file, the indicated RPM is about half of that, all across the board.

The erratic "worst knock value" reading (jagged black lines all across the top field) also seems to indicate some sort of interference. In my own experience with VEMS, this "worst knock value" reading seems to spike when there is an ignition misfire (I still have the factory coil, can't keep up, have Peep's wasted spark setup on the shelf).

I would start by cleaning the bellhousing grounds, followed by checking the speed/reference mark sensor condition and gaps. Take a close look at the engine side of the speed/ref mark harness, and consider replacing it with the Lindsey repair harness section.

If all of the above seems OK, it could be something with the ignition system itself----maybe crappy ignition wires causing electromagnetic interference with the speed/ref sensors? Non-resistor spark plugs?

"Good" start:




"Bad" start:

Droops83

What boost level is your MBC set to?

Go into the "Base Setup">"Rev Limit/Overrun/Safety" menu and see what your overboost fuel cut is set to. I left mine at the default value of 250 kPa, which is 1.5 bar of boost pressure (~22 PSI). If this is set below your target boost level, then you can raise it. And yes, a hard fuel cut is like hitting a wall!

Cyberpunky

Wow nice work Chris. I can't see any of that looking at those screen shots.
I have LR harness, and know grounds are good, but I only mention that for anyone who reads this down the track. I have all the gear ready to go for wasted spark and it sound like that will fix the issue ?.
Cheers

Droops83

I'm not sure that installing the wasted spark system will be the cure----Wayne has this installed and seems to have the same intermittent issue. Post some datalogs here of good and bad running and we can see if it is the same.

In Wayne's case, it appears that something is interfering with the engine speed sensor output. I am by no means an electronics expert, but I do know that anything electrically "noisy" like a spark plug wire/ignition coil, noisy alternator, or a fuel injector is capable of causing interference with more sensitive circuits like the Bosch variable reluctance (VR) speed sensors. The original Bosch ML3.1 DME had a custom-designed chip to convert the analog 130+1 signal into a usable digital square wave, and it was quite robust. While the VEMS seems to be one of the few aftermarket ECUs capable of working with the 130+1 setup, it does seem to be much more sensitive to interference and/or wiring/ground issues, sensor air gap, etc. A conventional 60-2 or 36-1 tooth setup is simply much more forgiving in this aspect.

Proper diagnosis of the issue would require an oscilloscope and experimentation with isolating any noise sources, but we can start by getting some reliable data in the form of logs and going from there.